Reliable and security-aware communication in hybrid wireless networks

Abstract

The present invention relates to a wireless system 100 running multiple applications simultaneously, for example for both lighting control and asset tracking. Nodes 200 included in the wireless system 100 are capable of operating in multiple communication modes, where each communication mode is according to a different communication technology. On the other hand, considering that some applications can have higher security requirements than others, one application can have a preferred communication mode that is different from another application. In view of this, a mode switching method is disclosed to help the nodes 200 to serve multiple concurrent applications in an efficient manner.

Description

Technical Field

[0001] This invention relates to the field of wireless communication systems. More particularly, this document discloses various methods, apparatuses, systems, and computer-readable media related to communication methods of nodes in a wireless system comprising multiple nodes. Background Technology

[0002] A growing trend in the professional lighting market is the increasing move towards connected lighting systems, enabling a wide range of new features such as (remote) dispatching, energy monitoring, sensor-based lighting control, and asset management. In many cases, these systems are installed in existing buildings, where wireless networks are preferred to avoid the need for new cabling (for lighting control) to be deployed through the ceiling. Examples of such wireless network protocols widely used in current practice include open standards such as Zigbee, Thread, Bluetooth Low Energy (BLE), BLE Mesh, Wi-Fi, Wi-Fi Direct, and various proprietary network implementations built on top of IEEE 802.15.4, IEEE 802.15.1, or IEEE 802.11 standards.

[0003] Zigbee networks allow for multi-hop communication between devices in a mesh topology. In addition to mesh networking capabilities, Zigbee devices offer reduced power consumption and cost, making them attractive for large-scale deployments in wireless control systems, such as wireless lighting systems.

[0004] In indoor environments, location-based systems—such as Real-Time Location Systems (RTLS)—can also be deployed to locate and track assets, such as equipment and personnel. For example, asset tags attached to assets (e.g., laptops) can emit beacon signals, which can be received by sensors located at fixed locations. For ease of link configuration, the beacon signals can be transmitted via BLE radio.

[0005] WO2018228883A1 relates to a system and method for extending the coverage of a wireless single-hop network (e.g., a BLE network) by relaying messages of a wireless single-hop network over a wireless multi-hop network (e.g., a ZigBee mesh network), which benefits from the combined single-hop / multi-hop (e.g., BLE / ZigBee) capability of a wireless combining device that can seamlessly bridge between two wireless networks.

[0006] EP3255949A1 relates to a method for communicating between a combined endpoint device, a wireless router, and a wireless communication device, the method comprising monitoring a communication pattern of wireless data communication between the wireless router and the radio communication circuitry of the combined endpoint device, and storing data indicating the communication time of the wireless router based on the monitored communication pattern.

[0007] WO2020043592A1 relates to a system for selecting one or more devices in a wireless network to transmit, receive, and / or process radio frequency signals for presence and / or location detection. The system includes at least one processor configured to: determine the suitability of each of a plurality of devices for transmitting, receiving, and / or processing radio frequency signals for presence and / or location detection; select a subset of devices from the plurality of devices based on the suitability determined for each of the plurality of devices; and instruct at least one of the device subset to act as a device for transmitting, receiving, and / or processing radio frequency signals for presence and / or location detection. Summary of the Invention

[0008] The inventors recognized the advantage of reusing the same infrastructure of a lighting control system for asset tracking, allowing nodes to be configured to operate in one communication mode primarily for lighting control, or in another primarily for asset tracking. Lighting systems offer unique advantages for asset tracking, or Real-Time Tracking and Storage (RTLS), because the density of electrical equipment (luminaires) supports a dense sensor network for locating and tracking objects. While the preferred communication mode for lighting control differs from the preferred communication mode for asset tracking, it is possible to deploy nodes capable of supporting multiple communication modes to meet the requirements of different applications.

[0009] In view of the above, this disclosure relates to methods, apparatus, systems, computer programs, and computer-readable media for providing mechanisms related to communication methods of control nodes, thereby facilitating the hybrid application of systems in an efficient manner. More particularly, the object of the invention is achieved by the node as claimed in claim 1, the wireless control system as claimed in claim 7, the communication method as claimed in claim 9, and the computer program of the node as claimed in claim 10.

[0010] According to a first aspect of the invention, a node is provided. A node for communication in a wireless system, the node comprising: a controller configured to determine a default communication mode among multiple communication modes based on a role assigned to the node, wherein the role is related to an activity to be performed by the node, and the multiple communication modes include a first communication mode capable of supporting a mesh or tree topology with multi-hop routing according to a first communication technology, and a second communication mode capable of supporting a star topology with point-to-point connections according to a second communication technology; and a radio unit configured to: either operate in the first communication mode as the default communication mode and, upon instruction from the controller, switch to the second communication mode and send a notification message in the second communication mode, and then switch back to the first communication mode; or operate in the second communication mode as the default communication mode and, upon another instruction from the controller, switch to the first communication mode and receive another data or control packet in the first communication mode, and then switch back to the second communication mode; and wherein the controller is further configured to generate an instruction to switch from the first communication mode to the second communication mode based on the security level of a data or control packet recently received by the radio unit in the first communication mode or by the node itself; and to generate another instruction to switch from the second communication mode to the first communication mode based on another notification message received by the radio unit in the second communication mode.

[0011] This node supports multiple (two or more) communication modes, including a first communication mode and a second communication mode. The primary communication mode will be the node's default operating mode. Preferably, the first communication mode is based on the Zigbee standard, which is widely used in home automation and lighting control applications. The Zigbee network layer itself supports both star and tree networks as well as general mesh networking. Its robust topology control provides great flexibility in control systems, especially for reaching destination nodes far from the source node via direct links or one-hop links. In a preferred configuration, the second wireless communication technology conforms to the BLE standard. Advantageously, the point-to-point connection based on the second communication technology can also be a point-to-multipoint connection. The simple setup of point-to-point or point-to-multipoint connections (e.g., via BLE beacons) is highly beneficial for establishing links between tag devices and sensor nodes in asset tracking systems. Alternatively, the node can also support other communication modes for another purpose of the node or another application supported by the system.

[0012] A radio unit may include one or more transceivers to implement multiple communication modes, such that a transceiver may support only one communication mode, or a transceiver may support more than one communication mode. In a preferred embodiment, the radio unit is a combined transceiver supporting both a first communication mode and a second communication mode.

[0013] In one example, the radio unit could be a Zigbee and BLE combined device. Therefore, a node with such a combined transceiver can switch between primary and secondary communication modes on a time-sharing basis, which is a very cost-effective way to implement different applications within the same wireless system. Since the primary communication mode is the node's default operating mode, the radio unit will remain in the primary communication mode for most of its time or a large portion of its duty cycle.

[0014] The switching from the primary communication mode to another communication mode does not follow a fixed schedule but is based on a triggering event, which improves the system's reliability and flexibility. Preferably, the triggering event is an instruction generated by the controller based on the attributes of a packet, either recently received by the radio unit in the primary communication mode or recently generated by the node itself. In response to such an instruction, the radio unit temporarily switches to another communication mode among multiple communication modes to transmit or receive using that mode, and then switches back to the primary communication mode. Therefore, by default, the node operates in the primary communication mode to serve the main application, and can then temporarily switch to another communication mode to support another application enabled in the system.

[0015] The packet could be a packet recently received from another node in the wireless system or from another device in the surrounding environment during primary communication mode. It could also be a packet recently generated by the node itself. For example, the node could be the source of the application packet, generating a new packet to be distributed across the network to a destination node, rather than being received from another node. Other devices in the surrounding environment could be new tag devices or sensor devices placed in the surrounding environment.

[0016] In one embodiment, the attributes of a group are at least one of the following: group type, group security level, and information contained in the group.

[0017] This instruction is generated by the controller based on the attributes of the most recently received or generated packets. Depending on the assigned role or primary communication mode, different aspects of the most recently received or generated packets may be considered. In some scenarios, these aspects may also be considered in a joint manner, allowing one or more aspects to be combined.

[0018] Advantageously, the type of packet can be a data packet, a control packet, a beacon, or a notification message.

[0019] Depending on the application being enabled, different types of packets can be transmitted in a wireless system. Some packets can flow between nodes serving the same type of application, while others can be delivered to other nodes primarily serving a different type of application.

[0020] For example, lighting control information can be assembled into control packets that are distributed to most nodes in a lighting control system, including some nodes that serve asset tracking applications in default mode. On the other hand, beacons from tag devices may only be of interest to nodes primarily assigned to asset tracking applications, and less relevant to other nodes primarily assigned to lighting control.

[0021] To forward lighting control packets to nodes primarily assigned to asset tracking applications, the security level of the control packets can be considered. For example, a point-to-point connection based on a second communication technology might be considered less secure compared to a first communication technology. It's possible that control packets with lenient security requirements can be sent directly via the second communication mode, while control packets with strict security requirements can only circulate via the first communication mode. Then, to allow some nodes primarily operating in the second communication mode to receive such control packets, a notification message can be first sent to those nodes via the second communication mode to trigger them to switch to the first communication mode to receive the actual control packets.

[0022] In another example, the notification message may further include address information for a different communication mode, which can be a unicast address, a multicast address, or a combination of both. Although the notification message itself can be sent as an announcement to all neighboring nodes, only the node addressed by the address information can be triggered to switch to the other communication mode.

[0023] In another embodiment, the notification message indicates scheduling information related to switching to the first communication mode, which may be at least one of the following:

[0024] - Delay, after which, upon receiving the notification message, the radio unit should switch to the first communication mode, and

[0025] - The node should remain in the first communication mode for the duration of the communication mode.

[0026] To coordinate the primary communication mode with other communication modes more promptly, it is advantageous that recently received or generated packets also more accurately indicate when a node needs to switch to another communication mode. Such scheduling or planning of nodes can be very efficient, allowing them to be pre-aligned with another anticipated receiver or transmitter for transmission or reception activities in a different communication mode.

[0027] Specifying the duration or dwell time for a node when temporarily switching to another communication mode can also be beneficial for recently received or generated packets. For example, specifying a duration can help a node avoid unnecessary long wait times in another communication mode, taking into account potential packet loss due to poor channel conditions in that mode.

[0028] In another embodiment, the notification message includes unicast or multicast address information for communication in the second communication mode.

[0029] To help nodes send or receive in a different communication mode during temporary switching, it is beneficial to include address information for use in the other communication mode within the most recently received or generated packets. For example, when a node temporarily switches to another communication mode, the message to be sent can be addressed as a unicast message to a single destination, or as a multicast message to a set of specified destinations. And this is then more efficient than broadcast messages because only the addressed node will take further action.

[0030] In another example, the information included in the group specifies the assignment that will be performed by the node when it temporarily switches to another communication mode.

[0031] In one example, the allocation could be associated with the reception of a broadcast message with a dedicated sequence number or packet identifier. In another example, the allocation could be associated with the successful delivery of a packet to the intended destination node, such that the allocation is considered to have been completed only after an acknowledgment (ACK) message has been received from the intended destination node.

[0032] Advantageously, roles can be assigned to nodes based on at least one of the following: node location, pre-defined system configuration, context-dependent runtime node configuration, and application deployment scheme of the wireless system.

[0033] The primary communication mode is determined based on the role assigned to a node or the main activity the node will perform. Role assignment can be related to predefined system or node configurations, system-level or network-level application deployment schemes, the node's physical location, or context-dependent runtime configurations. For example, when multiple nodes are deployed in a neighboring area, it might be effective to designate the first node primarily for lighting control and its neighboring nodes primarily for asset tracking. Therefore, the first node could primarily operate in Zigbee mode to detect lighting control-related packets and then switch to BLE mode as needed to forward some lighting control information to neighboring nodes, or to forward triggers to neighboring nodes, potentially requiring it to collect temporarily stored messages.

[0034] In one embodiment, the role assigned to a node is a router node, which facilitates communication between nodes in the wireless system.

[0035] In wireless systems, different types of communication messages may flow between nodes. For example, wireless communication can be used to distribute remote control commands, for remote configuration, or for remotely collecting sensor data between a central controller and nodes. Wireless communication can also occur between nodes in the system, for example, for distributed control.

[0036] In a preferred configuration, the controller is further configured to determine the first communication mode as the primary communication mode, and the radio unit is further configured to operate primarily in the first communication mode to support communication between nodes in a wireless system with multi-hop routing.

[0037] Advantageously, the nodes primarily designated for remote control operate as router nodes according to the first communication technology. The wireless system is then divided into a core mesh network and numerous smaller star networks surrounding each router node; the core mesh network includes all nodes designated as router nodes. The neighbors of a router node can be assigned to other applications, which then rely on the router node to send or receive information from a remote location.

[0038] In another embodiment, the role assigned to the node is an asset tracking sensor.

[0039] This node can also act as another type of sensor, primarily operating in one communication mode or the main communication mode. And sometimes, the sensor node needs to switch to another communication mode to send collected sensing data or receive information from another network.

[0040] In another preferred configuration, the controller is also configured to determine the second communication mode as the primary communication mode, and the radio unit is also configured to operate primarily in the second communication mode for receiving beacon signals from the tag device of the asset tracking system.

[0041] Advantageously, the asset tracking sensor operates in a second communication mode, either point-to-point or point-to-multipoint. Therefore, as an asset tracking sensor, the node is configured to receive beacon signals from one or more tag devices within direct communication range.

[0042] According to a second aspect of the present invention, a wireless system is provided. The wireless system includes a plurality of nodes according to the present invention.

[0043] Wireless systems can be used for a variety of applications. In one example, it's used for building automation in offices or homes, or for industrial control in factories. In another example, the control system can be used as a monitoring system for security surveillance. Or, as mentioned above, wireless systems can also be used for asset tracking and lighting control. Given that network capacity can often far exceed the actual throughput requirements of a single application, it's also beneficial to use the same wireless control system to support one or more applications to improve efficiency.

[0044] The advantage is that the wireless system is a wireless lighting control system.

[0045] In a preferred configuration, the wireless system is used for lighting control, such as for controlling switches, sensors, and lamps. The wireless system can also be used to collect status information and sensing data from actuators and sensors arranged with or near the lamps.

[0046] According to a third aspect of the present invention, a communication method is provided. A communication method for a node in a wireless system, the method comprising the node...

[0047] - Determine a default communication mode among multiple communication modes based on the role assigned to the node, wherein the role is related to the activity to be performed by the node, and the multiple communication modes include a first communication mode that can support a mesh or tree topology with multi-hop routing according to a first communication technology, and a second communication mode that can support a star topology with point-to-point connections according to a second communication technology.

[0048] - Either operate in the first communication mode as the default communication mode, and switch to the second communication mode and send a notification message in the second communication mode according to the instruction, and then switch back to the first communication mode; or operate in the second communication mode as the default communication mode, and switch to the first communication mode according to another instruction and receive another data or control packet in the first communication mode, and then switch back to the second communication mode.

[0049] - Generate an instruction to switch from the first communication mode to the second communication mode based on the security level of data or control packets received in the first communication mode or generated by the node itself; and

[0050] - Generate another instruction to switch from the second communication mode to the first communication mode based on another notification message received in the second communication mode.

[0051] In a preferred configuration, a first communication mode is determined as the default communication mode, and the method further includes a node: primarily operating in the first communication mode to support communication between nodes in a remotely controlled or multi-hop routing wireless system; generating instructions based on the attributes of a packet recently received in the first communication mode or recently generated by the node itself; and, based on the generated instructions, temporarily switching to a second communication mode to send a notification message, and then switching back to the first communication mode.

[0052] In another preferred configuration, the second communication mode is determined as the default communication mode, and the method further includes a node that primarily operates in the second communication mode for receiving beacon signals from the tag device of the asset tracking system; generating instructions based on a notification message recently received or generated in the second communication mode; and, based on the generated instructions, temporarily switching to the first communication mode for a certain duration or performing an assignment, and then switching back to the second communication mode.

[0053] The invention can be further embodied in a computer program that includes code means which, when executed by a node including a processing means, causes the processing means to perform the method according to the invention. Attached Figure Description

[0054] In the accompanying drawings, similar reference numerals are used throughout. Figure 1 Generally, the same parts are referred to. Furthermore, the accompanying drawings are not necessarily to scale; instead, the focus is usually on illustrating the principles of the invention.

[0055] Figure 1 A schematic architecture of a wireless system comprising multiple nodes for executing more than one application is illustrated.

[0056] Figure 2 The basic components of a node in a wireless system are illustrated schematically.

[0057] Figure 3 Exemplary network architectures with combined nodes are shown according to various embodiments; and

[0058] Figure 4 A flowchart illustrating the communication method of nodes in a wireless system is shown. Detailed Implementation

[0059] Various embodiments of the invention will now be described based on a wireless system 100 comprising multiple nodes 200, such as... Figure 1As shown. Wireless system 100 can be a local network under the control of local coordinator 400 to serve a specific control purpose or for data collection, and the local coordinator can then be further connected to a local application server 500. In another example, the system can be connected to a cloud, backbone network, or remote server 500 via local coordinator, gateway, bridge, or router device 400. In a lighting environment, node 200 can be included in lighting equipment, illuminators, sensors, or switches for communication functions of the lighting equipment, illuminators, sensors, or switches. Node 200 can also be included in HVAC systems, smart refrigerators, smart ovens, other smart white goods, or another sensor or actuator, or a remote controller in a broader building / home automation environment.

[0060] In addition to the wireless control application implemented by node 200, another application can be supported in wireless system 100. In one example, this other application could be asset tracking. Assets can be people or objects, such as computers, medical devices, packages, etc. Assets can have or include tag devices 300. For example, each tag device 300 can be attached to a corresponding asset. Each tag device 300 can include a transmitter to transmit wireless signals 350, such as beacon signals that include identification (ID) information of the asset and / or the tag device. For example, the tag device 300 can transmit beacon signals that conform to wireless standards, such as the BLE standard. Therefore, some nodes 200 in the wireless system can be configured to also operate as asset sensor nodes to receive such beacons from the tag devices 300.

[0061] Figure 2 The basic components of a node 200 for communication in a wireless system 100 are schematically depicted. Node 200 includes a radio unit 210 capable of operating multiple communication modes, including at least a first communication mode capable of supporting a mesh or tree network with multi-hop routing, and a second communication mode capable of supporting point-to-point connections. Radio unit 210 may include a single transceiver that is a combined device supporting at least the first and second communication modes, and operates on a time-sharing basis according to one of the multiple communication modes each time. In another example, radio unit 210 may include at least two separate transceivers 220, 230. The at least two separate transceivers 220, 230 may be single-mode transceivers, and each supports a communication protocol. It is also possible that of the at least two separate transceivers 220, 230, one is a combined device and the other is a single-mode device. Node 200 also includes a controller 240 configured to determine a primary communication mode from the multiple communication modes based on a role assigned to the node.

[0062] Optionally, node 200 may also include an application controller and / or actuator, such as Figure 2 As indicated in 250. The application controller or actuator can be associated with the control functions of a node in a lighting environment, a broader building automation environment, an asset tracking environment, or another application. The application controller and / or actuator can execute control commands received by the node. Status information is provided as feedback to the control system by the application controller and / or actuator.

[0063] In another option, node 200 may further include sensors, such as Figure 2 As indicated by 260 in the diagram. Sensor 260 can be configured to detect presence and / or environmental information, such as temperature, humidity, etc. Sensing data can be collected in addition to, or independently of, the state information of the node or application controller and / or actuator.

[0064] Depending on the application enabled by the communication interface of wireless system 100 and node 200—for example, whether it is a variety of communication modes supported by the node—the disclosed invention can be implemented in several different scenarios. For ease of description, the different scenarios are explained by using Zigbee as an example of a first communication protocol and BLE as an example of a second communication protocol.

[0065] Figure 3 Exemplary network architectures with combined nodes according to various embodiments are illustrated. Bright nodes are configured as router nodes primarily operating in a first communication mode with routing capabilities enabled. Dark nodes are configured as asset tracking sensor nodes primarily operating in a second communication mode for receiving sensed data or for point-to-point connections. Router node 200 is operable to distribute control commands to multiple nodes 200 and forward status information from multiple nodes 200 via multi-hop routing. Thus, the router nodes construct a sparse multi-hop network according to a first communication technology, which acts as a core network of the wireless system 100. A considerable number of non-router nodes may be located around each router node 200 with a one-hop direct link. For broadcast messages, non-router nodes can receive them directly from at least one nearby router node. Optionally, non-router nodes may also be configured to operate primarily according to a second communication protocol, for example, to support a second application in addition to the main application performed by the wireless network. In this scenario, in order to deliver messages to such non-router nodes, the router node may expend additional effort to switch to operation according to the second communication protocol on demand, or the non-router node may need to periodically switch between the two operating modes in order to obtain messages from the wireless network.

[0066] Therefore, the first wireless communication protocol primarily enables large-scale information distribution and collection in wireless control systems with multiple nodes, which can be used for lighting control and / or building automation. Importantly, the first wireless communication protocol supports multi-hop routing, which can be Zigbee, Thread, Bluetooth mesh, Wi-Fi mesh, WirelessHART, SmartRF, CityTouch, IP500, Z-wave, or any other mesh or tree-based technology.

[0067] Preferably, the second communication protocol conforms to the Bluetooth Low Energy (BLE) standard. It can also be Wi-Fi Direct, Zigbee Inter-PAN, Zigbee Touchlink, or another wireless communication standard that facilitates simple setup for point-to-point connections.

[0068] Assuming that two communication systems operating under the first and second communication protocols can use different modulation schemes, different frequency plans, and different time schedules, a potential benefit of the local star network around each router node operating under the second communication protocol is that mutual interference can be significantly reduced compared to homogeneous networks.

[0069] The availability of so-called combined radio chips (such as Zigbee / BLE and BLE / Wi-Fi chips) – in which two wireless protocol stacks share a single radio front-end in the time domain – enables new features for lighting IoT systems. These new features include direct control of wireless lighting via BLE connectivity from a mobile phone, locating a mobile phone via BLE signals transmitted from the wireless lighting system, and tracking assets via mobile BLE tags. While combined radio chips offer significant advantages in lighting systems, system design must also address a common limitation: a proper balance must be struck between the performance of traditional lighting control and the performance of the added new features. This common limitation stems from the fact that while there are two radio protocol stacks, only one radio front-end must be shared between the two stacks; for example, the Zigbee / BLE combination is “blind” on BLE but active (transmitting, receiving, or idle listening) on ​​Zigbee, and vice versa. Poor management can lead to a significant degradation in the performance of at least one radio protocol.

[0070] This invention proposes an operational method in lighting IoT or other wireless networks that uses a combined radio chip to reliably perform more than one function. An example is a lighting IoT network where each node has a combined radio chip that needs to perform traditional lighting control or data collection functions (via Zigbee or Wi-Fi) and asset tracking functions (using BLE). The system can also consist of nodes, each comprising multiple individual radio chips. And then scheduling multiple communication modes on a time-sharing basis is not critical. However, given that different short-range wireless communication technologies and energy efficiencies share the same frequency band, avoiding scenarios where nodes simultaneously enable more than one communication mode remains highly beneficial.

[0071] In one example, tag device 300 periodically transmits BLE beacons, which are received by nodes 200 in lighting network 100 using their combined radio chips. Measurement data of the BLE beacons is collected, and the results are transmitted over lighting network 100 using the Zigbee protocol. To make lighting control and asset tracking feasible and reliable, it is disclosed that a fixed set of nodes is designated as routers that operate only or primarily in Zigbee mode, while the remaining nodes operate in both Zigbee and BLE modes. This set of routers will remain in Zigbee operation to provide connectivity throughout the wireless system. Non-router nodes will be primarily configured in BLE mode, but will be in Zigbee mode when they have something to send or receive in Zigbee mode (e.g., to / from / via router nodes). The reason for non-router nodes operating primarily in BLE mode is to facilitate the reception of BLE beacon signals from the tag device. The longer a non-router node can operate in BLE mode, the better its performance in receiving BLE signals from the tag device, and therefore the better the battery life of the tag device, since the beacon transmission rate can be reduced without compromising tracking performance.

[0072] The diagram of this network configuration is shown in Figure 3The diagram illustrates that bright nodes are router nodes used for lighting control applications, while dark nodes are non-router nodes primarily used for asset tracking. If there are enough Zigbee router nodes, nearby non-router nodes can send information over the lighting control network without issue. However, if the non-router nodes primarily operate in BLE mode, they may have problems receiving Zigbee messages and thus likely miss a significant portion of Zigbee packets. One option is to use an "end device" role in Zigbee, where bright nodes are the parent nodes of either end devices or dark nodes. The parent node then stores messages for its child nodes, and the child nodes need to periodically poll the parent node for any messages intended for them. Polling has the disadvantage of a delay in the arrival of messages sent to non-router nodes. This delay averages about half the polling cycle, with a maximum of one polling cycle. Reducing this delay by implementing (more)frequent polling by the end devices is undesirable, as this would negatively impact asset tracking performance. Therefore, the inventors recognized that it was advantageous to reduce latency by sending a notification from the parent node to the terminal device that there was something for them to pick up via another communication mode (which in this example is Zigbee mode).

[0073] In another example, without using the "end device" mechanism according to the Zigbee standard, a router node that needs to send messages to non-router nodes will first switch to BLE and send a notification message to the non-router nodes. The notification message can be a short message containing no or only partial application content. The router node then switches back to Zigbee mode and only then (i.e., after the non-router has also switched to Zigbee) sends messages to the non-router nodes via Zigbee. When the non-router receives the notification message in BLE mode, it switches to Zigbee mode to receive the actual application message and then immediately returns to BLE mode, ensuring that the primary allocation of asset tracking is not significantly affected for the non-router nodes. In cases where the notification message does not contain application content, the actual application message is typically longer and contains the complete application content; or it contains partial application content that, together with the partial application content transmitted in the notification message, represents the complete application content.

[0074] Furthermore, Zigbee communication can be fully secure because each node, upon joining the network, is part of the same Zigbee network and will be subject to standard Zigbee security, or even additional application-level security. On the other hand, while the simple setup of point-to-point connections in BLE mode is very attractive, announcements are generally not protected by the BLE standard specification. Some application data from Zigbee networks with more stringent security requirements may not be suitable for direct transmission via BLE announcement messages. Transmitting announcements instead of actual application data presents far fewer security challenges for the protection of the announcements, or makes implementing appropriate security mechanisms much more straightforward or simple. Moreover, if security is required, application-layer security mechanisms can be applied to the BLE announcement data payload. And the distribution of security keys used for BLE announcements can be accomplished via the (already secure) Zigbee network.

[0075] Using the example from the previous section, bright nodes are Zigbee router nodes that operate only or primarily in Zigbee mode, while dark nodes are Zigbee non-router nodes that operate primarily in BLE mode for asset tracking. Zigbee router nodes need to be in Zigbee mode most of the time to continuously listen to the Zigbee network and maintain normal operation. Similarly, non-router nodes need to be in BLE mode most of the time to listen for BLE signals from tag devices. Therefore, the best way to send any packets from the control network or the Zigbee network to non-router nodes is in the mode in which they operate most frequently (i.e., BLE mode).

[0076] In one scenario, a bright node (router node) needs to send a broadcast message to all or many nodes in the network. This is typically a lighting control message triggered by a sensor or switch co-located with the bright node, but it can also originate from other sources (such as a scheduler, central controller, or another controller in the network). All expected nodes in the network need to receive it within a short time so that all expected lights operate synchronously in front of the user. The broadcast message is first sent in Zigbee mode, ensuring that all bright nodes can receive it according to the Zigbee broadcast protocol. Additionally, the bright node will send notifications in the form of short BLE beacons or announcements to reliably reach dark nodes (non-router nodes), as dark nodes are in BLE mode most of the time. These notifications simply inform nearby expected dark nodes to switch to Zigbee mode and listen for that mode. The Zigbee broadcast can be repeated several times by the bright Zigbee router node at certain intervals (e.g., 0.5 seconds), for example, 3-4 times. Each rebroadcast by a neighboring router node lasts approximately 100 ms. Therefore, if dark nodes quickly switch to Zigbee receive mode during the period before the Zigbee broadcast stops (this lasts approximately 1–1.5 seconds), they are likely to receive application data from the ongoing Zigbee broadcast, without needing to poll the parent node as described in the previous example. Thus, the benefits of the disclosed method include reduced latency (significantly less than the polling period and almost synchronized with the router node's reception) and reduced workload (no fixed polling period scheduled).

[0077] As an improvement, dark nodes can also quickly switch between BLE and Zigbee modes within the aforementioned duration, allowing them to spend some time in BLE mode without compromising their chances of receiving Zigbee broadcasts. Another improvement is that the notification uniquely identifies the Zigbee broadcast message, enabling a dark node to switch back to BLE once it successfully receives an instance of the Zigbee broadcast message, without having to wait for a repeat of the same message. This significantly improves the listening time for BLE. Otherwise, the entire asset tracking network could be "deaf" or "blind" for approximately 1-1.5 seconds during a Zigbee broadcast cycle. A combination of source address and sequence number can be used to uniquely identify the Zigbee broadcast message in the notification. A combination of source address, destination address, and sequence number can also be used to uniquely identify the Zigbee unicast message in the notification.

[0078] The system can be further improved by aligning the sending of notifications and Zigbee (re)broadcasts in bright nodes. Ideally, notifications to dark nodes should be sent exactly before the Zigbee (re)broadcast, so that nearby dark nodes will already be notified and prepared to receive the Zigbee (re)broadcast input by switching to Zigbee mode. This will require timely coordination between the two modes by the nodes. A further improvement is to include the expected time delay for starting the Zigbee (re)broadcast after sending the notification message in the notification, allowing dark nodes to better prepare their scheduling for receiving Zigbee broadcasts based on the estimated delay.

[0079] In another improvement, dark nodes can utilize the timing characteristics of Zigbee broadcasts. Zigbee rebroadcasts last approximately 100 ms with 0.5-second intervals. Dark nodes can choose to listen to Zigbee only after the expected 100 ms delay and switch back to their primary communication mode (BLE), only switching back to Zigbee again after 0.5 seconds for another 100 ms. In this way, dark nodes can spend a very limited amount of time on Zigbee without missing any broadcasts. Since this timing-related parameter can depend on the node firmware and / or network size, nodes may be configured (by the network initiator, central controller, and / or router nodes) to use certain timing values, or learn the optimal value through observation patterns. This approach can be used in conjunction with other embodiments / examples, such as a scheme where the dark node stops listening on Zigbee once it has successfully received the expected Zigbee broadcast message.

[0080] In another example, the non-routable dark node is a Zigbee end device that listens on the BLE channel as the default mode. Router nodes send notification messages as BLE advertisements to the non-routable dark node. Upon receiving, the non-routable dark node switches to Zigbee mode and checks its parent node according to the Zigbee protocol (as an end device) to receive the Zigbee (broadcast) data buffered by its parent node. In this way, the initiative rests entirely with the dark node to receive some data.

[0081] While the scenarios presented so far concern sending broadcast messages from the control network to nodes serving asset tracking applications, a similar mechanism can be applied to unicast messages. For unicast, the handover to Zigbee can be optimized by providing the Zigbee address of the intended receiver in the BLE notification message. Therefore, only the target receiver switches to Zigbee, while other receivers can remain on BLE listening for beacon signals from the tag device.

[0082] Figure 4A flowchart of a communication method 600 for node 200 in a wireless system is shown. In step S601, a primary communication mode is determined from multiple communication modes based on the role assigned to the node. These multiple communication modes include a first communication mode capable of supporting a mesh or tree topology with multi-hop routing according to a first communication technology, and a second communication mode capable of supporting a star topology with point-to-point connections according to a second communication technology. The method further includes step S602, where the node primarily operates in the primary communication mode; and step S603, where instructions are generated based on the attributes of packets recently received in the primary communication mode or recently generated by the node itself; and step S604, where, based on the generated instructions, the node temporarily switches to another communication mode among the multiple communication modes for transmitting or receiving using that other communication mode. Then, in step S605, the node switches back to the primary communication mode.

[0083] The method according to the invention can be implemented on a computer as a computer-implemented method, or in dedicated hardware, or in a combination of both.

[0084] The executable code of the method according to the invention can be stored on a computer / machine-readable storage device. Examples of computer / machine-readable storage devices include non-volatile memory devices, optical storage media / devices, solid-state media, integrated circuits, servers, etc. Preferably, the computer program product includes non-transitory program code means stored on a computer-readable medium for executing the method according to the invention, as disclosed in the above embodiments, when the program product is executed on a computer or a processing device included in a node or network or network access initialization device.

[0085] Methods, systems, and computer-readable media (transitory and non-transitory) may also be provided to implement selected aspects of the embodiments described above.

[0086] The term "controller" is generally used herein to describe, among other things, various means relating to the operation of one or more network devices or coordinators. A controller can be implemented in a variety of ways (e.g., using dedicated hardware) to perform the various functions discussed herein. A "processor" is an example of a controller employing one or more microprocessors, which can be programmed using software (e.g., microcode) to perform the various functions discussed herein. A controller can be implemented with or without a processor, and can also be implemented as a combination of dedicated hardware performing some functions and a processor (e.g., one or more programmed microprocessors and associated circuitry) performing other functions. Examples of controller components that can be employed in various embodiments of this disclosure include, but are not limited to, conventional microprocessors, application-specific integrated circuits (ASICs), and field-programmable gate arrays (FPGAs).

[0087] In various embodiments, the processor or controller may be associated with one or more storage media (collectively referred to herein as "memory," such as volatile and non-volatile computer memories, such as RAM, PROM, EPROM, and EEPROM, compact disks, optical disks, etc.). In some embodiments, the storage media may be encoded with one or more programs that, when executed on one or more processors and / or controllers, perform at least some of the functions discussed herein. Various storage media may be fixed within the processor or controller, or may be transportable, such that one or more programs stored thereon may be loaded into the processor or controller to implement various aspects of the invention discussed herein. The terms "program" or "computer program" are used herein in a general sense to refer to any type of computer code (e.g., software or microcode) that can be used to program one or more processors or controllers.

[0088] As used herein, the term “network” refers to any interconnection of two or more devices (including controllers or processors) that facilitates the transport of information (e.g., for device control, data storage, data exchange, etc.) between any two or more devices and / or between multiple devices coupled to the network.

[0089] Unless explicitly indicated otherwise, the indefinite articles “a” and “an” (“a” and “an”) used herein in the specification and claims shall be understood to mean “at least one”.

[0090] As used herein in the specification and claims, “or” should be understood to have the same meaning as “and / or” as defined above. For example, when separating items in a list, “or” or “and / or” should be interpreted as inclusive, i.e., including multiple elements or at least one of the elements in the list, but also including multiple elements or more than one of the elements in the list, and optionally, additional unlisted items. Only terms that explicitly indicate the opposite, such as “only one of…” or “exact one of…”, or when used in a claim, “consisting of…” will refer to including multiple elements or exactly one of the elements in the list. In general, the term “or” as used herein, when preceded by an exclusive term such as “any,” “one of…,” “only one of…,” or “exact one of…”, should only be interpreted as indicating an exclusive alternative (i.e., “one or the other, but not both”). “Substantially consisting of…” when used in a claim should have its ordinary meaning as used in the field of patent law.

[0091] As used herein in the specification and claims, the phrase "at least one" referring to a list of one or more elements should be understood to mean at least one element selected from any one or more elements in the list, but does not necessarily include at least one of every element specifically listed in the list, and does not exclude any combination of elements in the list. This definition also allows for the optional presence of elements other than those specifically identified in the list of elements referred to by the phrase "at least one," whether related to or unrelated to those specifically identified elements.

[0092] It should also be understood that, unless expressly indicated to the contrary, in any method claimed herein that includes more than one step or action, the order of the steps or actions of the method is not necessarily limited to the order in which the steps or actions of the method are described. Furthermore, the reference numerals appearing between parentheses in the claims (if any) are provided merely for convenience and should not be construed as limiting the claims in any way.

[0093] In the claims, and in the description above, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “accommodating,” “containing,” etc., shall be understood as open-ended, meaning including but not limited to. Only the transitional phrases “consisting of” and “substantially consisting of” shall be closed or semi-closed transitional phrases, respectively.

Claims

1. A node (200) for communicating in a wireless system (100), the node (200) comprising: A controller (240) is configured to determine a default communication mode among multiple communication modes based on a role assigned to the node, wherein the role is associated with an activity to be performed by the node, and the multiple communication modes include... • Capable of supporting a first communication mode with multi-hop routing in a mesh or tree topology based on a first communication technology, and • Capable of supporting a second communication mode with a star topology having point-to-point connections based on the second communication technology; - A radio unit (210) configured to operate in the first communication mode as the default communication mode, and, according to an instruction from the controller, switch to the second communication mode and send a notification message in the second communication mode, and then switch back to the first communication mode, the notification message including unicast or multicast address information for communication in the second communication mode, and wherein the notification message indicates scheduling information related to switching to the first communication mode, the scheduling information being at least one of the following: a delay after which, upon receiving the notification message, the radio unit (210) of another node should switch to the first communication mode, and the duration after which the other node (200) should remain in the first communication mode; The controller (240) is further configured to generate an instruction to switch from the first communication mode to the second communication mode based on the security level of data or control packets received by the radio unit in the first communication mode or generated by the node itself.

2. The node (200) according to claim 1, wherein, The notification message includes unicast or multicast address information for one or more intended destination nodes.

3. The node (200) according to claim 1 or 2, wherein, The role can be assigned to the node (200) based on at least one of the following: the node's location, the predefined system configuration, the context-dependent runtime node configuration, and the application deployment scheme of the wireless system.

4. The node (200) according to claim 1 or 2, wherein, The role assigned to the node (200) is a router node, used to facilitate communication between nodes in the wireless system.

5. The node (200) according to claim 4, wherein, The controller (240) is also configured to determine the first communication mode as the default communication mode, and the radio unit (210) is also configured to operate in the first communication mode for most of its duty cycle to support communication between nodes in the wireless system (100) with multi-hop routing.

6. A wireless system (100) comprising a plurality of nodes (200) as described in claim 1.

7. The wireless system (100) according to claim 6, wherein the wireless system (100) is a wireless lighting control system.

8. A communication method (600) for a node (200) in a wireless system (100), the method (600) comprising the node (200): - Determine (S601) a default communication mode from a plurality of communication modes based on the role assigned to the node (200), wherein the role is associated with the activity to be performed by the node, and the plurality of communication modes include • Capable of supporting a first communication mode with multi-hop routing in a mesh or tree topology based on a first communication technology, and • Capable of supporting a second communication mode with a star topology having point-to-point connections based on the second communication technology; - Operate in the first communication mode as the default communication mode (S602), and according to the instruction, switch to the second communication mode and send a notification message in the second communication mode, and then switch back to the first communication mode, wherein the notification message includes unicast or multicast address information for communication in the second communication mode, and wherein, The notification message indicates scheduling information related to switching to the first communication mode, the scheduling information being at least one of the following: a delay after which, upon receiving the notification message, the radio unit (210) of another node should switch to the first communication mode, and the duration after which the other node (200) should remain in the first communication mode; - Based on the security level of the data or control packets received in the first communication mode, generate (S603) an instruction to switch from the first communication mode to the second communication mode.

9. A computing program product comprising code or program, wherein when the program is executed by a node (200) including a processing device, the code means causes the processing device to perform the method of claim 8.

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